Cann based her "mitochondrial Eve" theory on a VERY small sample, n=147. That in itself is a statistical problem, i.e. sample is not representative of the population.

This is nonsense. You can't say this without knowing her Type I error criterion and the size of the effect she obtained. Only then you can know the statistical power of her study. Just sample size tells you NOTHING.

Also, Cann has comitted methodological errors that should not be overlooked.

You gave no proof of that, other than calling her sample size 'small', which is nonsense, if you know any statistics.

Well it would probably be on the cellular level since lineages would branch out so fast, and since transition between a old species and new species isn't clear, we probably weren't even primates yet. Think about it, a species is defined when a male and female can mate and have fertaile offspring, so lets say for example, a Donkey and Horse 100,000 years ago could have fertile offspring. They may have looked just as different from each other as they do today, but they'd be considered the same species.

This is the stuff that makes evolution so interesting to me. There is so much to learn about it, and what we do know is amazingly interesting.

"A patriot must always be ready to defend his country against his government." E.Abbey

I tend to support Wolpoff's Multiregional Hypothesis based on the fact the humans have maintained genetic continuity and species cohesiveness. There are multiple, not one, migrations out of Africa, beginning of course with H. erectus. Genetic drift quarantees persistence of regional populations that are further away from the 'center' of radiation (Africa). In these cases, interbreeding takes place; elsewhere replacement is possible. Big question: does interbreeding happens with Neaderthals? Recent DNA extracted from nead. says no. But in Asia local populations persist.

The multi-regional hybrid thesis is mainly based on forensic evidence of bones of hominid species found all over the world.

Nevertheless, there is one thing to be careful about: the fact that archaic humans and modern humans have similar physical characteristics in the same regions does not necessarily imply that they underwent the SAME mutations.

Mutations that adapt to the local climate survive, so therefore different mutations might yield the same result. For example, many Neanderthals were thought to have blond or red hair; yet the mutation that led to blond and red hair in Neanderthals was NOT the same that led to the same features in modern humans.

Even among modern humans, it has already been proven that Europeans and East Asians had distinct mutations that led to the whitening of the skin (between 10,000-20,000 years ago).

The study that you quoted was not the only experiment that yeilded the conclusion that Africans are more genetically diverse. Many other scientists, such as Spencer Wells, has travelled through distinct African populations and took blood samples; which did certainly lead to the same findings.

I thought that regarding Asians, it has already been proven that modern East Asians do not descend from Asian homo-eructus because the DNA samples of Asian homo-eructus had a host of mutation markers that modern Asians lack; and that modern Asians share the same mutation markers as modern Africans up until relatively few generations (about 5000); which would mean that modern Asians separated from africans well after they had separated from homo erectus.

If I would have to be convinced by the multi-regional model, they'd have to come up with more convincing genetic evidence; because the out-of-Africa model has been proved principally by DNA markers of modern populations rather than archaeological evidence.

Actually, sample size in hypothesis testing is related to Type II error, not Type I. Someone doesn't know their stats around here obviously but that's not me. Type II error occurs when, because of the non-representational nature of the sample, the hypothesis is rejected while it's true.

" I do disagree with what you say but I'll defend to my death your right to do so."

Actually, sample size in hypothesis testing is related to Type II error, not Type I. Someone doesn't know their stats around here obviously but that's not me. Type II error occurs when, because of the non-representational nature of the sample, the hypothesis is rejected while it's true.

In a documentary of National Geographic by the genetist Spencer Wells, he said that he had taken samples of between 2000-4000 samples from every population that he examined; and each sample was taken from distinct places. Although it can't be the absolute presentation, it is certainly a fair presentation.

According to what he examined, the San people of Africa are more genetically diverse than all non-Africans put together.

calvo, no one (at least not me) is arguing against the well-attested fact that modern humans originated in South Africa. It is the concept of a "single mother" that is becoming increasingly unfathomable. What Cann has done in her research is take the DNA of MODERN humans and deduce that of a single living being approx. 150,000 ya. by tracing back the number of mutations in the mtDNA. "Eves" DNA remains a mystery, never to be deciphered since we can't go and take hers. ALL we know is about the DNA of the modern sample. To extend that back is highly assumptive and scientifically erroneous since truly, "Eves" DNA will never be known, i.e. Cann's is a hypothesis that can never be truly tested. Theories of a single anything are highly dubious in uman evolution. With the known biodiversity of humans I consider it naive to think of "single mothers" or "single driving force" or single anything for that matter. Let me ask you this: what about "Eve's" ancestors? Why the cut-off point there? What if the ancestors had a recessive mutation that shows up every few generations? How Cann would know unless she went back in time?¬†¬†¬†

" I do disagree with what you say but I'll defend to my death your right to do so."

Actually, sample size in hypothesis testing is related to Type II error, not Type I. Someone doesn't know their stats around here obviously but that's not me. Type II error occurs when, because of the non-representational nature of the sample, the hypothesis is rejected while it's true.

'Sample size is related to type II error'? No it is not, it is an independent variable. You can choose it the way you like. It effects the statistical power (i.e. 1-Type II error probability) of your experiment. So if you choose a small number compared to the effect you are looking for, your experiment won't have much power.¬†

From what you have written, it is clear that you do not know¬†what 'statistical power' is. Or how to determine the number of samples in a statistical study. Alpha (i.e. type I error probability) is reqired to calculate the statistical power of an experiment, so you need to know it before commenting on the sample size.

I recommend that you stick your arrogance up somewhere safe and go and learn what statistical power is. If you want to pass your undergrad stats course that is.

calvo, no one (at least not me) is arguing against the well-attested fact that modern humans originated in South Africa. It is the concept of a "single mother" that is becoming increasingly unfathomable. What Cann has done in her research is take the DNA of MODERN humans and deduce that of a single living being approx. 150,000 ya. by tracing back the number of mutations in the mtDNA. "Eves" DNA remains a mystery, never to be deciphered since we can't go and take hers. ALL we know is about the DNA of the modern sample. To extend that back is highly assumptive and scientifically erroneous since truly, "Eves" DNA will never be known, i.e. Cann's is a hypothesis that can never be truly tested. Theories of a single anything are highly dubious in uman evolution. With the known biodiversity of humans I consider it naive to think of "single mothers" or "single driving force" or single anything for that matter. Let me ask you this: what about "Eve's" ancestors? Why the cut-off point there? What if the ancestors had a recessive mutation that shows up every few generations? How Cann would know unless she went back in time?

I thought you just contradicted yourself. Earlier on in another post you said that you were in favour of the "multi-regional" thesis; how come now you say that you believe that humans originated in Africa?

Of course we could detect ancient DNA though the modern population, because we INHERIT all the genetic mutation markers of our forebears. The DNA sample of our common ancestor would have a DNA that has all the mutation marks that we have in common.

If you read this thread from the beginning to the end, many forummers have explained that X-chromonzone Eve was not the only nor the first human being alive. It is only that the genes of all the rest of the people who lived at her time had faded away through natural selection.

If you can't understand it, check out this page. It has a very clear diagram:

Well, that's not the partial replacement theory I and most other anthropologists I talk to have in mind. The debate is not concerned with ORIGIN (so far firmly set to have taken place in Africa ca. 90 kya) but with rates and modes of migration. Are you sure you understand the extend of the debate? In a purely scientific sense, Cann's assertions can never be tested therefore they remain implications at best. Projecting today's population genetic make up back through time is science-by-proxy,¬†especially¬†in view of the most recent DNA research (Cann¬†conducted¬†hers 20-something years ago). In particular, we just know are starting to understand the role of non-coding DNA and especially that of the "junked" introns. Of course those are not part of mtDNA; but still, many issues remain in association with Y and X chromosome DNA polymorphisms such as restriction fragment length (RFLP's). Many technical points have arisen for which Cann had no idea about: a) some regions of mtDNA are less susceptible to change while others fix mutations at a higher rate, contributing to higher variability within a population b) the fact that all 37 genes of the mtDNA are closely linked limits their usefulness of the mitochondria in EVOLUTION studies (Spuhler, 1988) c) there is considerable difficulty in calculating a molecular "clock". On this last one, some calibrations assume a steady mutation rate (constant, steady change in base sequences) at 2%/million years while others point to a much slower rate of less than 1%. These calibrations are obtained by comparisons of LIVING human and ape mtDNA, mainly chimpanzee. The faster rate assumes that apes and humans diverged from a "common ancestor" some five¬†million¬†years ago (Templeton, 1985). The slower rate is mainly attested by paleontological evidence that places the time of the divergence much earlier, approx. 9 mya. This pushes the "eve" theory much further back and in accordance with the fossil record. ¬†Regardless, no one is arguing the origin of H. sapiens. But to embrace a far-fetched theory of a 'single mother' is ¬†naive,¬†especially¬†in the light of our constantly changing knowledge of DNA and genetics (what I've written is probably already obsolete).

Of course you can go ahead and believe what you wish; at least you're not quick with your characterizations like some other, trigger-happy members of this Forum. Personally, i believe in rigorous testing: there are no "sacred" truths in science. And I instinctively shy away from the various '-isms' encounered in the field, in this case a biodeterministic approach to heredity, variation, and evolution. ¬†¬†

" I do disagree with what you say but I'll defend to my death your right to do so."

GcleAgain, that we may all have a common ancestor doesn't prove (or even indicate) there was only one common ancestor

How can we not have "one common ancestor", we havn't existed since eternity so we must have had a starting point.

I meant one common human ancestor. For instance, as a minimum, the Eve everyone talks about could have been an identical twin.

More likely though is that there was a common human litter (i.e. group of siblings). More likely than that that there beings qualified as 'human' emerged in several families.

One difficulty here is that there would have been no discrete divide between 'human' and 'non-human' so one population gradually emerged from another population over many generations. After all no-one claims there was a common ancestor of all Anglo-Saxons, or all Han Chinese, so why a common ancestor of humans?

(And as I said, the concept of one single common ancestor rather than several is even more unlikely.)

Citizen of Ankh-Morpork
Never believe anything until it has been officially denied - Sir Humphrey Appleby, 1984.

Just to clarify, I am not saying that the Cann study is correct, or the number samples it has is enough. Maybe it is not a powerful study. What I am saying is, he provided no proof of that.

Once more, what I am saying is: it is nonsense to claim 'this study has just X samples, that is a very low'. That is not convincing. If someone writes this and still fails to acknowledge his error after it was pointed out, it means that that person has no idea about how to evaluate a statistical study.

Well, that's not the partial replacement theory I and most other anthropologists I talk to have in mind. The debate is not concerned with ORIGIN (so far firmly set to have taken place in Africa ca. 90 kya) but with rates and modes of migration. Are you sure you understand the extend of the debate? In a purely scientific sense, Cann's assertions can never be tested therefore they remain implications at best. Projecting today's population genetic make up back through time is science-by-proxy, especially in view of the most recent DNA research (Cann conducted hers 20-something years ago). In particular, we just know are starting to understand the role of non-coding DNA and especially that of the "junked" introns. Of course those are not part of mtDNA; but still, many issues remain in association with Y and X chromosome DNA polymorphisms such as restriction fragment length (RFLP's). Many technical points have arisen for which Cann had no idea about: a) some regions of mtDNA are less susceptible to change while others fix mutations at a higher rate, contributing to higher variability within a population b) the fact that all 37 genes of the mtDNA are closely linked limits their usefulness of the mitochondria in EVOLUTION studies (Spuhler, 1988) c) there is considerable difficulty in calculating a molecular "clock". On this last one, some calibrations assume a steady mutation rate (constant, steady change in base sequences) at 2%/million years while others point to a much slower rate of less than 1%. These calibrations are obtained by comparisons of LIVING human and ape mtDNA, mainly chimpanzee. The faster rate assumes that apes and humans diverged from a "common ancestor" some five million years ago (Templeton, 1985). The slower rate is mainly attested by paleontological evidence that places the time of the divergence much earlier, approx. 9 mya. This pushes the "eve" theory much further back and in accordance with the fossil record. Regardless, no one is arguing the origin of H. sapiens. But to embrace a far-fetched theory of a 'single mother' is naive, especially in the light of our constantly changing knowledge of DNA and genetics (what I've written is probably already obsolete).

Of course you can go ahead and believe what you wish; at least you're not quick with your characterizations like some other, trigger-happy members of this Forum. Personally, i believe in rigorous testing: there are no "sacred" truths in science. And I instinctively shy away from the various '-isms' encounered in the field, in this case a biodeterministic approach to heredity, variation, and evolution.

I'm not believing in what I wish to believe in. I believe in what the latest science proves.

Can you show me a source demonstrating that Europeans inherit DNA mutation markers from European homo-eructus, and Asians from Asian homo-eructus.

If you could show me such scientific proof, then I would certainly take your point into consideration.

The "X-chromozone" Eve is not only based on Cann's investigation. Have you checked out the links that I sent you?

Genetic investigation is still going on taking an ever-larger blood sample of every population in the world; and most test result point to the same conclusion.

You're right that Cann's sample is small. But The "GENOGRAPHIC" poject has taken a VERY LARGE sample and they are still taking more.

I do not have a source about about Asian H. erectus. I do not think anyone has extracted their DNA. That is a major source of conflict: I believe that using today's DNA to answer questions about extinct humans only answers part of the question. However, Asians today retain primitive characteristics such as shovel-shaped incisors and occipital bun (both H. erectus traits). If indeed complete replacement is true, then these mutations have repeated twice in EXACT fashion which is an evolutionary¬†impossibility (or at least not seen anywhere else yet). Also, Java man is of high antiquity which presupposes that if modern H. sapiens completely replaced them, they must have arrived there immediately upon exit from Africa. we can't fully nswer because we don't qite know about rate of migration out of Africa.

Neaderthal DNA was successfully extracted from four European¬†individuals¬†and tests show that the two are not related, i.e. modern humans replaced¬†Neanderthals¬†in Europe. However, there are issues with¬†contamination¬†that remain pending. So far, in Europe, the complete replacement stand true untill more evidence comes up.¬†

A lot of people tend to focus on genetic evidence and completely forget about the fossil record. In my opinion that is a mistake. It is very possible that in Asia modern humans out of Africa mated with local H. erectus/Archaic homo to produce the modern inhabitants. This is the partial replacement model that I generally tend to favor. The question is not "out of Africa" or not. The question is whether they bred with each other or not, very different. ¬†

" I do disagree with what you say but I'll defend to my death your right to do so."

I do not have a source about about Asian H. erectus. I do not think anyone has extracted their DNA. That is a major source of conflict: I believe that using today's DNA to answer questions about extinct humans only answers part of the question. However, Asians today retain primitive characteristics such as shovel-shaped incisors and occipital bun (both H. erectus traits). If indeed complete replacement is true, then these mutations have repeated twice in EXACT fashion which is an evolutionary impossibility (or at least not seen anywhere else yet). Also, Java man is of high antiquity which presupposes that if modern H. sapiens completely replaced them, they must have arrived there immediately upon exit from Africa. we can't fully nswer because we don't qite know about rate of migration out of Africa.

Neaderthal DNA was successfully extracted from four European individuals and tests show that the two are not related, i.e. modern humans replaced Neanderthals in Europe. However, there are issues with contamination that remain pending. So far, in Europe, the complete replacement stand true untill more evidence comes up.

A lot of people tend to focus on genetic evidence and completely forget about the fossil record. In my opinion that is a mistake. It is very possible that in Asia modern humans out of Africa mated with local H. erectus/Archaic homo to produce the modern inhabitants. This is the partial replacement model that I generally tend to favor. The question is not "out of Africa" or not. The question is whether they bred with each other or not, very different.

That's a quite interesting point you made about certain characteristics being inherited from homo-erectus.

Let's see if the DNA testing result of Asian homo erectus could actually confirm this.

Another not-so-clear point is regarding the date during which modern humans left Africa. Some claim to be as early as 85000 years ago and others clain to be as late as 50000 years ago (a big difference).

Genetic testing shows that all native Americans descend from a emigration wave from Siberia that happened between 15000 and 20000 years ago; yet forensic evidence revealed the existence of modern humans in America at much earlier dates.

Well, we can't get Asian H. erectus DNA. DNA decays rapidly and they were barely able to extract the European¬†Neanderthal¬†DNA at about 40,000 BCE. We'll never know about the genetic make up of H. erectus, except by comparison with modern populations which is not really conclusive.

So, the fossil record is al we have for that period (and modern genetic studies that can infer).

" I do disagree with what you say but I'll defend to my death your right to do so."

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